Infiniti FX35, FX50 (S51). Manual - part 1589

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< DTC/CIRCUIT DIAGNOSIS >

U1000 CAN COMM CIRCUIT

DTC/CIRCUIT DIAGNOSIS

U1000 CAN COMM CIRCUIT

Description

INFOID:0000000005241708

• CAN (Controller Area Network) is a serial communication line for real time applications. It is an on board

multiplex communication line with high data communication speed and excellent error detection ability. A
modern vehicle is equipped with many ECMs, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, two control units are connected
with two communication lines (CAN H-line, CAN L-line) allowing a high rate of information transmission with
less wiring. Each control unit transmits/receives data but selectively reads required data only.

• It transmits the vehicle status to pre-crash seat belt control unit using the CAN communication system.
• It consists of CAN system (unified meter and A/C amp., ICC sensor, BCM, steering angle sensor).
• Refer to 

LAN-29, "CAN System Specification Chart"

 in LAN section for CAN communication unit (2WD).

DTC Logic

INFOID:0000000005241709

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

SELF-DIAGNOSIS WITH PRE-CRASH SEAT BELT CONTROL UNIT

1.

Turn ignition switch ON and wait for 2 seconds or more.

2.

Check “Self-diagnostic result” with CONSULT-III.

Is any DTC detected?

YES

>> Refer to 

LAN-29, "CAN System Specification Chart"

 in LAN section for CAN communication or

CAN system.

NO

>> CAN communication system is normal.

DTC No.

Self-diagnosis 

item

DTC Detection Condition

Possible causes

U1000

CAN communi-

cation circuit

Pre-crash seat belt control unit cannot transmit and receive 
CAN communication system for 2 seconds or more. 

CAN message reception 
malfunction 

B2451 SEAT BLT MTR DR CIRC

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B2451 SEAT BLT MTR DR CIRC

Description

INFOID:0000000005241710

• It pulls, returns, and maintains according to the motor rotation.
• It is built into the seat belt retractor.
• It is installed to back of driver side center pillar garnish.

DTC Logic

INFOID:0000000005241711

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

SELF-DIAGNOSIS WITH PRE-CRASH SEAT BELT CONTROL UNIT

1.

Turn ignition switch ON.

2.

Check “Self-diagnostic result” with CONSULT-III.

Is DTC detected?

YES

>> Refer to 

SBC-15, "Diagnosis Procedure"

.

NO

>> Driver side pre-crash seat belt motor system is normal.

Diagnosis Procedure

INFOID:0000000005241712

1.

INSPECTION START

1.

Check “Self-diagnostic result” with CONSULT-III.

2.

Touch “ERASE”.

3.

Perform DTC Confirmation Procedure.
See 

SBC-15, "DTC Logic"

.

Is DTC B2451 displayed again?

YES

>> Replace pre-crash seat belt control unit (driver side).

NO

>> GO TO 2.

2.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-36, "Intermittent Incident"

.

>> INSPECTION END

DTC No.

Self-diagnosis item

DTC Detection Condition

Possible causes

B2451

SEAT BLT MTR DR 
CIRC

Circuit of seat belt motor (driver side) is 
open or shorted

Control unit internal malfunction 

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< DTC/CIRCUIT DIAGNOSIS >

B2452 SEAT BLT MTR AS CIRC

B2452 SEAT BLT MTR AS CIRC

Description

INFOID:0000000005241713

• It pulls, returns, and maintains according to the motor rotation.
• It is built into the seat belt retractor.
• It is installed to the back of passenger side center pillar garnish.

DTC Logic

INFOID:0000000005241714

DTC DETECTION LOGIC

DTC REPRODUCTION PROCEDURE

1.

SELF-DIAGNOSIS WITH PRE-CRASH SEAT BELT CONTROL UNIT

1.

Turn ignition switch ON.

2.

Check “Self-diagnostic result” with CONSULT-III.

Is DTC detected?

YES

>> Refer to 

SBC-16, "Diagnosis Procedure"

.

NO

>> Passenger side pre-crash seat belt motor system is normal.

Diagnosis Procedure

INFOID:0000000005241715

1.

INSPECTION START

1.

Check “Self-diagnostic result” with CONSULT-III.

2.

Touch “ERASE”.

3.

Perform DTC Confirmation Procedure.
See 

SBC-16, "DTC Logic"

.

Is DTC B2452 displayed again?

YES

>> Replace pre-crash seat belt control unit (passenger side).

NO

>> GO TO 2.

2.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-36, "Intermittent Incident"

.

>> INSPECTION END

DTC No.

Self-diagnosis item

DTC Detection Condition

Possible causes

B2452

SEAT BLT MTR AS CIRC

Circuit of seat belt motor (pas-
senger side) is open or shorted

Control unit internal malfunction 

B2453 BR STROKE SEN CIRC

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B2453 BR STROKE SEN CIRC

Description

INFOID:0000000005241716

• It changes voltage according to brake pedal depressed amount and sends the signal to pre-crash seat belt

control unit.

• There are 2 signals (brake pedal stroke sensor 1 and 2) sent from the brake pedal stroke sensor. Pre-crash

seat belt control unit judges the stroke amount and the speed of the brake pedal according to the voltage of
the signal sent by each side.

• It is installed to back of driver instrument panel (lower).

DTC Logic

INFOID:0000000005241717

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.

SELF-DIAGNOSIS WITH PRE-CRASH SEAT BELT CONTROL UNIT

1.

Turn ignition switch ON.

2.

Check “Self-diagnostic result” with CONSULT-III.

Is DTC detected?

YES

>> Refer to 

SBC-17, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000005241718

1.

CHECK PRE-CRASH SEAT BELT CONTROL UNIT INPUT SIGNAL

1.

Turn ignition switch ON.

2.

Select “BRK PEDAL SNSR1” and “BRK PEDAL SNSR2” in “DATA MONITOR” mode with CONSULT-III. 

3.

Check “BRK PEDAL SNSR1” and “BRK PEDAL SNSR2” indication under the following conditions.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> GO TO 2.

2.

CHECK BRAKE PEDAL STROKE SENSOR POWER SUPPLY

1.

Turn ignition switch OFF.

2.

Disconnect brake pedal stroke sensor connector.

3.

Check voltage between Brake pedal stroke sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> GO TO 4.

DTC No.

Self-diagnosis item

DTC Detection Condition

Possible causes

B2453

BR STROKE SEN 

CIRC

Circuit of brake pedal stroke sensor 
output is open or shorted

• Open circuit, short circuit to battery, and short 

circuit to ground in brake pedal stroke sensor 
harness 

• Control unit internal malfunction 
• Brake pedal stroke sensor malfunction

Monitor item

Condition

Voltage (V)

(Approx.)

BRK PEDAL SNSR1

Brake released 

→

 depressed

1 

→

 4

BRK PEDAL SNSR2

4 

→

 1

Brake pedal stroke sensor

Ground

Voltage (V)

(Approx.)

Connector

Terminal

E111

2

5